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A209962
Number of (n+1) X 2 0..3 arrays containing all values 0..3 with every 2 X 2 subblock having one or two distinct values, and new values 0..3 introduced in row major order.
1
0, 0, 9, 162, 1845, 17262, 144945, 1138194, 8548029, 62230230, 442977705, 3101305338, 21442016565, 146833223166, 998073454689, 6745063632354, 45376569607725, 304167049525926, 2033050559738265, 13557845469637962
OFFSET
1,3
COMMENTS
Column 1 of A209969.
LINKS
FORMULA
Empirical: a(n) = 16*a(n-1) - 83*a(n-2) + 132*a(n-3) + 56*a(n-4) - 88*a(n-5) - 32*a(n-6).
Empirical g.f.: 9*x^2*(1 + 2*x) / ((1 - x)*(1 - 4*x)*(1 - 5*x - 2*x^2)*(1 - 6*x - 4*x^2)). - Colin Barker, Jul 14 2018
EXAMPLE
All solutions for n=4:
..0..1....0..1....0..0....0..0....0..0....0..0....0..0....0..0....0..1
..1..0....0..0....0..0....0..0....1..0....0..0....1..1....0..1....0..1
..1..1....2..2....1..1....1..1....0..0....1..1....2..1....0..0....0..0
..2..2....2..3....2..2....2..2....2..2....2..2....2..2....2..2....2..2
..2..3....2..2....3..3....3..2....2..3....2..3....2..3....2..3....2..3
CROSSREFS
Cf. A209969.
Sequence in context: A159831 A133793 A319197 * A084874 A158749 A300843
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 16 2012
STATUS
approved